for a pdf copy of this article click on the following link:
Water Conservation and Reuse, The Value of Wastewater
Executive Summary
The key to water conservation is reuse. Reusing water already paid for reduces overall cost. Reuse would aid in lowering peak demands and therefore would reduce the cost of providing a basic water supply.
In Boerne it would lower the demand on groundwater used for peaking, effectively increasing both quality and quantity of groundwater throughout Kendall County.
In a typical development, if 407,313,750 gallons (1,250 acre feet) of water were used, then 372,000,000 (1,141 acre feet) would be estimated as wastewater return flow. The cost of treated water from GBRA is about $750.00 an acre foot. In this case, the value of available reuse water from return flow each year would more than $850,000.
A report produced for the Guadalupe-Blanco River Authority (GBRA) exploring the concept of a building two regional wastewater facilities to serve eastern Hays County, identified significant reduction in water demand through treated effluent reuse. Most notable is the recognition that it is most beneficial where both need and source are close.
The study made a direct comparison to the State recommended strategy of using large regional plants to one that featured smaller multiple plants. Analysis showed the Multiple Plants Model provided the lowest cost per housing unit and the highest reuse.
The Boerne Master Plan notes Physical Growth/Expansion Trends. In all directions, health and safety issues dictate the need reliable and affordable wastewater service for residents within the City limits.
In 2004, an initial needs assessment was conducted for the City by HDR Engineering, Inc. The wastewater capacity required was based on the population estimates at full build out within the city limits over a 20 year planning period and was limited to the population served by the water supply of the City. The estimated capacity required was 2.5 MGD.
However, a new demand from Esperanza appears to have had significant influence in the preferred site selection for a new facility that could be expanded to 3.9 MGD. This factor must be considered when deciding who pays for this extra capacity and where to put it.
Finally, the City should take the lesson of others in the area and move away from considering the use of large, regional plants. Though they may work well in densely populated urban areas, they are not suitable for the Hill Country.
Instead, support the continued use of the Multiple Plant Model to increase both quality and quantity of both surface and groundwater throughout Kendall County.
Water Conservation and Reuse in Kendall County
The State Water Plan factors conservation into future water availability for all Texans.
Water conservation offers significant advantages to we who live in Kendall County as well. The key to water conservation is reuse.
Reusing water already paid for reduces overall cost. Reuse would aid in lowering peak demands and therefore would reduce the cost of providing a basic water supply.
In Boerne it would lower the demand on groundwater used for peaking, effectively increasing both quality and quantity of groundwater throughout Kendall County.
You Can’t Manage What Can’t Count
Usually it’s water availability that drives the news when it comes to growth. Lately, the topic has shifted to the equally important task of processing the water after it’s been used.
The basic factors used to determine the size of a Wastewater Treatment Plant (WWTP) are prescribed by the Texas Commission for Environmental Quality (TCEQ). It’s a simple worksheet called a Developers Bond Application Report Format (BARF).
These step-by-step instructions are provided to water districts as they prepare their bond application for submittal to the TCEQ. The BARF explains basic water requirements.
The common denominator is the Equivalent Single-Family Connection or ESFC. One ESFC is equal to a typical detached single-family house. Furthermore, “Unless otherwise justified by usage data or required by applicable rule, law or regulatory requirement, an ESFC is equivalent to a single-family residence with 3.0 persons.”
To get an idea of what this means to a development’s wastewater, as well as water needs, consider this TCEQ guidance: “Unless a local governmental authority requires otherwise, or unless otherwise established, an ESFC is defined as 360 Gallons Per Day (GPD) for average water usage and 300 GPD for average wastewater return flow.”
In order to account for all non-residential (commercial) connections and all multi-family residential (apartments) connections must be expressed in ESFCs using actual metered average water usage. If not yet available, projected water usages would be considered. To get this number, you could simply use the ESFC GPD factor described above.
In this case, the average return flow would be about 10,000 gallons per month of wastewater for a single-family residence. A commercial building using an average of 100,000 gallons per month of wastewater would be rated at 10 ESFCs.
As a practical example, Esperanza promises to provide all the water it will need through a Guadalupe-Blanco River Authority (GBRA) contract of 1,250 acre feet of surface water from Canyon Lake.
In simple math, this could yield 3100 ESFCs. This would seem reasonable to meet the basic needs (minus peaking) of the advertised 2,480 single family homes and leaves additional capacity for multi-family residential and commercial connections.
It also means of the 407,313,750 gallons (1,250 acre feet) used, 372,000,000 (1,141 acre feet) would be estimated as wastewater return flow. The cost of treated water from GBRA is about $750.00 an acre foot. In this case, the value of available reuse water from return flow each year would more than $850,000.
Maximizing a Re-use System
By United States Geologic Survey (USGS) definition, return flow is water that is returned to surface or ground water, after use or wastewater treatment, and thus becomes available for reuse. Return flow can go directly to surface water, directly to ground water through an injection well or infiltration bed, or indirectly to ground water through septic systems.
A key feature of the Esperanza development is the intent to save water through reuse. A report produced for the Guadalupe-Blanco River Authority (GBRA) exploring the concept of a building two regional wastewater facilities to serve eastern Hays County, identified significant reduction in water demand through treated effluent reuse. Most notable is the recognition that it is most beneficial where both need and source are close.
Perhaps more importantly, the study made a direct comparison to the State recommended strategy of using large regional plants to one that featured smaller multiple plants. In the final analysis, the Smaller Multiple Plants provided the lowest cost per housing unit, as well as highest amount of reuse.
Additionally, the potential for reuse with the Multiple Plant Model would also aid in lowering peak demands and therefore would reduce the cost of providing a basic water supply. In a conjunctive water system like that of Boerne, it would lower the demand on groundwater used for peaking, effectively increasing both quality and quantity of groundwater throughout Kendall County.
Finding a Site for a Wastewater Treatment Plant
When designing a WWTP an engineer’s best friend is gravity. More gravity means less the cost. Seen from above, creek beds are logical indicators of the gravity flow. In this case, page 2-15 of the Boerne Master Plan gives a quick view of these creek systems.
Stormwater
The rolling terrain in and around Boerne allows for quick and sudden drainage of storm water. The fallen water, pulled by gravity, runs down elevation until it reaches the extensive creek system that is located throughout Boerne. Figure 2-19 shows the extensive creek system in Boerne. All of the creeks eventually converge into Cibolo Creek.
Viewing this page presents many options for placement of a WWTP. The confluence of Brown’s Creek and Cibolo Creek is one. The drainage anywhere upstream of this confluence gives an indication of other possible locations.
Less desirable locations can be accommodated through engineering solutions such as lift stations currently used around Boerne, but this increases costs.
Meeting the Wastewater Needs of Kendall County
Throughout Kendall County, several examples of the Multiple Plant Model application already exist. Tapatio Springs Resort is one. Another is Cordillera Ranch. This WWTP is built to GBRA specifications. When complete, it will be operated by GBRA. Both make good use of treated wastewater for irrigation onsite.
Water conservation offers significant advantages to we who live in Kendall County as well. The key to water conservation is reuse.
Reusing water already paid for reduces overall cost. Reuse would aid in lowering peak demands and therefore would reduce the cost of providing a basic water supply.
In Boerne it would lower the demand on groundwater used for peaking, effectively increasing both quality and quantity of groundwater throughout Kendall County.
You Can’t Manage What Can’t Count
Usually it’s water availability that drives the news when it comes to growth. Lately, the topic has shifted to the equally important task of processing the water after it’s been used.
The basic factors used to determine the size of a Wastewater Treatment Plant (WWTP) are prescribed by the Texas Commission for Environmental Quality (TCEQ). It’s a simple worksheet called a Developers Bond Application Report Format (BARF).
These step-by-step instructions are provided to water districts as they prepare their bond application for submittal to the TCEQ. The BARF explains basic water requirements.
The common denominator is the Equivalent Single-Family Connection or ESFC. One ESFC is equal to a typical detached single-family house. Furthermore, “Unless otherwise justified by usage data or required by applicable rule, law or regulatory requirement, an ESFC is equivalent to a single-family residence with 3.0 persons.”
To get an idea of what this means to a development’s wastewater, as well as water needs, consider this TCEQ guidance: “Unless a local governmental authority requires otherwise, or unless otherwise established, an ESFC is defined as 360 Gallons Per Day (GPD) for average water usage and 300 GPD for average wastewater return flow.”
In order to account for all non-residential (commercial) connections and all multi-family residential (apartments) connections must be expressed in ESFCs using actual metered average water usage. If not yet available, projected water usages would be considered. To get this number, you could simply use the ESFC GPD factor described above.
In this case, the average return flow would be about 10,000 gallons per month of wastewater for a single-family residence. A commercial building using an average of 100,000 gallons per month of wastewater would be rated at 10 ESFCs.
As a practical example, Esperanza promises to provide all the water it will need through a Guadalupe-Blanco River Authority (GBRA) contract of 1,250 acre feet of surface water from Canyon Lake.
In simple math, this could yield 3100 ESFCs. This would seem reasonable to meet the basic needs (minus peaking) of the advertised 2,480 single family homes and leaves additional capacity for multi-family residential and commercial connections.
It also means of the 407,313,750 gallons (1,250 acre feet) used, 372,000,000 (1,141 acre feet) would be estimated as wastewater return flow. The cost of treated water from GBRA is about $750.00 an acre foot. In this case, the value of available reuse water from return flow each year would more than $850,000.
Maximizing a Re-use System
By United States Geologic Survey (USGS) definition, return flow is water that is returned to surface or ground water, after use or wastewater treatment, and thus becomes available for reuse. Return flow can go directly to surface water, directly to ground water through an injection well or infiltration bed, or indirectly to ground water through septic systems.
A key feature of the Esperanza development is the intent to save water through reuse. A report produced for the Guadalupe-Blanco River Authority (GBRA) exploring the concept of a building two regional wastewater facilities to serve eastern Hays County, identified significant reduction in water demand through treated effluent reuse. Most notable is the recognition that it is most beneficial where both need and source are close.
Perhaps more importantly, the study made a direct comparison to the State recommended strategy of using large regional plants to one that featured smaller multiple plants. In the final analysis, the Smaller Multiple Plants provided the lowest cost per housing unit, as well as highest amount of reuse.
Additionally, the potential for reuse with the Multiple Plant Model would also aid in lowering peak demands and therefore would reduce the cost of providing a basic water supply. In a conjunctive water system like that of Boerne, it would lower the demand on groundwater used for peaking, effectively increasing both quality and quantity of groundwater throughout Kendall County.
Finding a Site for a Wastewater Treatment Plant
When designing a WWTP an engineer’s best friend is gravity. More gravity means less the cost. Seen from above, creek beds are logical indicators of the gravity flow. In this case, page 2-15 of the Boerne Master Plan gives a quick view of these creek systems.
Stormwater
The rolling terrain in and around Boerne allows for quick and sudden drainage of storm water. The fallen water, pulled by gravity, runs down elevation until it reaches the extensive creek system that is located throughout Boerne. Figure 2-19 shows the extensive creek system in Boerne. All of the creeks eventually converge into Cibolo Creek.
Viewing this page presents many options for placement of a WWTP. The confluence of Brown’s Creek and Cibolo Creek is one. The drainage anywhere upstream of this confluence gives an indication of other possible locations.
Less desirable locations can be accommodated through engineering solutions such as lift stations currently used around Boerne, but this increases costs.
Meeting the Wastewater Needs of Kendall County
Throughout Kendall County, several examples of the Multiple Plant Model application already exist. Tapatio Springs Resort is one. Another is Cordillera Ranch. This WWTP is built to GBRA specifications. When complete, it will be operated by GBRA. Both make good use of treated wastewater for irrigation onsite.
Another example is Kendall County Water Control and Improvement District (WCID) No. 1. This water district provides potable water to customers in the Comfort area and recycled water for irrigation of the adjacent golf course.
Clearly, several smaller facilities are more efficient than one large facility. In part this reflects economy of scale. Though economy of scale is a recognized cost factor for water supply systems, the same cannot be said for wastewater systems.
Meeting the Wastewater Needs of Boerne
The City of Boerne’s WWTP on Esser Road currently serves areas only the within City limits. The last expansion was completed just over 10 years ago. The following chronology is useful.
In 1996, it was expanded to the current permitted capacity of 1.2 Million Gallons per Day (MGD). It was designed to be expanded to a capacity of 2.4 MGD based on the current effluent discharge permits.
In 2001, City Staff became aware the WWTP was nearing its maximum capacity. By 2004, population increases and the corresponding residential and commercial customers, as well as increased infiltration and inflow from rainfall, the plant reached 75% of capacity. This triggered State requirements for a redesign.
In 2004, an initial needs assessment was conducted for the City by HDR Engineering, Inc. The wastewater capacity required was based on the population estimates at full build out within the city limits over a 20 year planning period and was limited to the population served by the water supply of the City.
From these projections it was determined the ultimate capacity needed was 3.9 MGD. Note: A recent two part story in the Boerne Star acknowledged the ultimate capacity could as high as 5.4 MGD.
In 2005, based on a 3.9 MGD capacity, the City Council authorized City Staff to explore an expansion of the existing site to 2.4 MGD and proceed with the acquisition of a second site for a WWTP.
In July 2007, the Preliminary Wastewater Process and Site Evaluation Report by HDR Engineering, Inc. notes six sites were actually evaluated by City Staff and HDR. But this was after the "City" decided to evaluate locations to support a new (or replacement) wastewater treatment plant that could be expanded beyond 2.4 MGD instead of operating two facilities perpetually.
Ultimately, an upgrade to the existing facility was deemed too expensive. However, this was based in part on questionable water test data collected during drought conditions. Funding for a new test was approved by City Council in October. The results will not be known for at least a year.
This explains how a single WWTP, ultimately capable of processing 3.9 GPD, expandable to 5.4 MGD, came to be. It also serves to explain the location because a facility this large would now also be subject to a small number of possible sites.
Given these basic facts, it is legitimate to ask if all options for a waste water treatment are on the table when meeting the current and future wastewater needs of Boerne.
Future testing could show a 2.4 MGD is feasible at the existing location. Infrastructure improvements could lessen the impact of seasonal rains. In both cases, a smaller facility, consistent with the Small Plant Model, could be best suited for future customers beyond the City limits.
Other Wastewater Needs of Boerne
The Boerne Master Plan notes Physical Growth/Expansion Trends on page 2-12. In all directions, health and safety issues dictate the need reliable and affordable wastewater service for residents within the City limits.
“The City of Boerne is currently expanding in all directions. Although major growth and expansion is occurring along I-10 in a southern direction, significant growth and expansion is occurring north, east, and west along the major roadway corridors. Figure 2-18 illustrates the current growth trends. It is anticipated that future development will continue to occur in these general outward directions.”
To the north is the Adler extension and Main Street to I-10 where commercial and industrial development is increasing.
West of I-10 at Cascade Caverns is the newly annexed Isbell Ranch as well as the Miller tract.
Also west of I-10 toward Boerne Lake are developments along Ranger Creek Road. These existing developments have experienced significant health and safety issues related to wastewater and water. New services could replace degraded septic systems and failing wells.
Moving east on State Highway 46 is Esperanza where a high residential demand for City wastewater may be created in the near future.
Each of these growth corridors is well suited to be served by the Smaller Multiple Plan wastewater concept. Additionally, this strategy could reduce water costs and lessen demand.
Meeting the Wastewater Needs of Esperanza
It is this new demand from Esperanza that appears to have had significant influence in the preferred site selection for a new facility that could be expanded to 3.9 MGD.
This resulted in the logical, but incompatible placement of a new WWTP at the confluence of the Cibolo and Menger Creeks, in the heart of the Cibolo Nature Center.
Because the site selection was justified as the lowest cost option for City of Boerne rate payers, it is also proper to consider the financial capability available to Kendall County WCID No. 2 and the developer of Esperanza.
Typically, these water districts take on the responsibility to finance, maintain and operate the water and sewer plants, the water distribution, as well as wastewater collection and drainage systems, for their customers within their boundaries.
For a developer, the most important aspect is their ability to issue tax-free municipal bonds to partially finance the construction of water, sewer and drainage utilities. These bonds are approved by the Texas Commission for Environmental Quality (TCEQ) with tax and debt limitations much more attractive than those offered to cities.
Recommendation: Marlin Atlantis and partners should consider constructing a wastewater collection, processing and re-use distribution system using Kendall County WCID No. 2, on site at Esperanza.
This would reduce the demand, and cost, to the City for wastewater. It would reduce peak demand and save groundwater permitted for the City of Boerne. Finally, it could eliminate the need for a new site on Cibolo Creek.
Compromise on both sides could lay the foundation for the success of Esperanza and allow Boerne to prosper without sacrificing those institutions and natural resources that contribute so greatly to our quality of life and make this community so unique.
Negotiations for a Development Agreement between the City and Esperanza are underway. Should the City opt to take on this additional demand, it is imperative wastewater reuse be not just considered, but become a mandatory feature.
The Bottom Line
The City should do all possible to preserve the capital investment previously made in the current WWTP. This includes the potential cost savings by modernizing the entire network of the existing infrastructure to reduce inflow and infiltration. The money saved through the integration of reuse water must be an integral part of any financial analysis.
The wastewater treatment management strategy of even ten years ago has changed dramatically. Keeping unit cost to the rate payer low is a top priority, but also be aware current available water resources are finite. Conservation is the name of game today.
In anticipation of major future growth, the City of Boerne has acted proactively to secure more water. The same proactive approach could easily be applied to wastewater treatment. The ultimate goal would be to adopt a Land Use Master Plan that incorporates reuse as a standard development tool.
The City should take the lesson of others in the local area and move away from considering the use of large, regional plants. Though they may work well in densely populated urban areas, they are not suitable for the Hill Country. Instead, support the continued use of the Multiple Plant Model. This is the best way to maximize the potential for reuse.
In future applications, this use of a small plant systems and reuse would aid in lowering peak demands and therefore would reduce the cost of providing a basic water supply to all customers.
In a conjunctive water system like that of Boerne, it would lower the demand on groundwater used for peaking, effectively increasing both quality and quantity of groundwater throughout Kendall County.
Milan J. Michalec
11 Nov 07
Clearly, several smaller facilities are more efficient than one large facility. In part this reflects economy of scale. Though economy of scale is a recognized cost factor for water supply systems, the same cannot be said for wastewater systems.
Meeting the Wastewater Needs of Boerne
The City of Boerne’s WWTP on Esser Road currently serves areas only the within City limits. The last expansion was completed just over 10 years ago. The following chronology is useful.
In 1996, it was expanded to the current permitted capacity of 1.2 Million Gallons per Day (MGD). It was designed to be expanded to a capacity of 2.4 MGD based on the current effluent discharge permits.
In 2001, City Staff became aware the WWTP was nearing its maximum capacity. By 2004, population increases and the corresponding residential and commercial customers, as well as increased infiltration and inflow from rainfall, the plant reached 75% of capacity. This triggered State requirements for a redesign.
In 2004, an initial needs assessment was conducted for the City by HDR Engineering, Inc. The wastewater capacity required was based on the population estimates at full build out within the city limits over a 20 year planning period and was limited to the population served by the water supply of the City.
From these projections it was determined the ultimate capacity needed was 3.9 MGD. Note: A recent two part story in the Boerne Star acknowledged the ultimate capacity could as high as 5.4 MGD.
In 2005, based on a 3.9 MGD capacity, the City Council authorized City Staff to explore an expansion of the existing site to 2.4 MGD and proceed with the acquisition of a second site for a WWTP.
In July 2007, the Preliminary Wastewater Process and Site Evaluation Report by HDR Engineering, Inc. notes six sites were actually evaluated by City Staff and HDR. But this was after the "City" decided to evaluate locations to support a new (or replacement) wastewater treatment plant that could be expanded beyond 2.4 MGD instead of operating two facilities perpetually.
Ultimately, an upgrade to the existing facility was deemed too expensive. However, this was based in part on questionable water test data collected during drought conditions. Funding for a new test was approved by City Council in October. The results will not be known for at least a year.
This explains how a single WWTP, ultimately capable of processing 3.9 GPD, expandable to 5.4 MGD, came to be. It also serves to explain the location because a facility this large would now also be subject to a small number of possible sites.
Given these basic facts, it is legitimate to ask if all options for a waste water treatment are on the table when meeting the current and future wastewater needs of Boerne.
Future testing could show a 2.4 MGD is feasible at the existing location. Infrastructure improvements could lessen the impact of seasonal rains. In both cases, a smaller facility, consistent with the Small Plant Model, could be best suited for future customers beyond the City limits.
Other Wastewater Needs of Boerne
The Boerne Master Plan notes Physical Growth/Expansion Trends on page 2-12. In all directions, health and safety issues dictate the need reliable and affordable wastewater service for residents within the City limits.
“The City of Boerne is currently expanding in all directions. Although major growth and expansion is occurring along I-10 in a southern direction, significant growth and expansion is occurring north, east, and west along the major roadway corridors. Figure 2-18 illustrates the current growth trends. It is anticipated that future development will continue to occur in these general outward directions.”
To the north is the Adler extension and Main Street to I-10 where commercial and industrial development is increasing.
West of I-10 at Cascade Caverns is the newly annexed Isbell Ranch as well as the Miller tract.
Also west of I-10 toward Boerne Lake are developments along Ranger Creek Road. These existing developments have experienced significant health and safety issues related to wastewater and water. New services could replace degraded septic systems and failing wells.
Moving east on State Highway 46 is Esperanza where a high residential demand for City wastewater may be created in the near future.
Each of these growth corridors is well suited to be served by the Smaller Multiple Plan wastewater concept. Additionally, this strategy could reduce water costs and lessen demand.
Meeting the Wastewater Needs of Esperanza
It is this new demand from Esperanza that appears to have had significant influence in the preferred site selection for a new facility that could be expanded to 3.9 MGD.
This resulted in the logical, but incompatible placement of a new WWTP at the confluence of the Cibolo and Menger Creeks, in the heart of the Cibolo Nature Center.
Because the site selection was justified as the lowest cost option for City of Boerne rate payers, it is also proper to consider the financial capability available to Kendall County WCID No. 2 and the developer of Esperanza.
Typically, these water districts take on the responsibility to finance, maintain and operate the water and sewer plants, the water distribution, as well as wastewater collection and drainage systems, for their customers within their boundaries.
For a developer, the most important aspect is their ability to issue tax-free municipal bonds to partially finance the construction of water, sewer and drainage utilities. These bonds are approved by the Texas Commission for Environmental Quality (TCEQ) with tax and debt limitations much more attractive than those offered to cities.
Recommendation: Marlin Atlantis and partners should consider constructing a wastewater collection, processing and re-use distribution system using Kendall County WCID No. 2, on site at Esperanza.
This would reduce the demand, and cost, to the City for wastewater. It would reduce peak demand and save groundwater permitted for the City of Boerne. Finally, it could eliminate the need for a new site on Cibolo Creek.
Compromise on both sides could lay the foundation for the success of Esperanza and allow Boerne to prosper without sacrificing those institutions and natural resources that contribute so greatly to our quality of life and make this community so unique.
Negotiations for a Development Agreement between the City and Esperanza are underway. Should the City opt to take on this additional demand, it is imperative wastewater reuse be not just considered, but become a mandatory feature.
The Bottom Line
The City should do all possible to preserve the capital investment previously made in the current WWTP. This includes the potential cost savings by modernizing the entire network of the existing infrastructure to reduce inflow and infiltration. The money saved through the integration of reuse water must be an integral part of any financial analysis.
The wastewater treatment management strategy of even ten years ago has changed dramatically. Keeping unit cost to the rate payer low is a top priority, but also be aware current available water resources are finite. Conservation is the name of game today.
In anticipation of major future growth, the City of Boerne has acted proactively to secure more water. The same proactive approach could easily be applied to wastewater treatment. The ultimate goal would be to adopt a Land Use Master Plan that incorporates reuse as a standard development tool.
The City should take the lesson of others in the local area and move away from considering the use of large, regional plants. Though they may work well in densely populated urban areas, they are not suitable for the Hill Country. Instead, support the continued use of the Multiple Plant Model. This is the best way to maximize the potential for reuse.
In future applications, this use of a small plant systems and reuse would aid in lowering peak demands and therefore would reduce the cost of providing a basic water supply to all customers.
In a conjunctive water system like that of Boerne, it would lower the demand on groundwater used for peaking, effectively increasing both quality and quantity of groundwater throughout Kendall County.
Milan J. Michalec
11 Nov 07
